Olefin polymers such as polyethylene, polypropylene, which may be atactic or stereospecific, such as isotactic or syndiotactic, and ethylene-higher alpha olefin copolymers, such as ethylene-propylene copolymers can be produced under various polymerization conditions and employing various polymerization catalysts. Such polymerization catalysts include Ziegler-Natta catalysts and non-Ziegler-Natta catalysts, such as metallocenes and other transition metal catalysts which are typically employed in conjunction with one or more co-catalysts. The polymerization catalysts may be supported or unsupported.
The alpha olefin homopolymers or copolymers may be produced under various conditions in polymerization reactors which may be batch type reactors or continuous reactors. Continuous polymerization reactors typically take the form of loop-type reactors in which the monomer stream is continuously introduced and a polymer product is continuously withdrawn. For example, polymers such as polypropylene, polyethylene or ethylene-propylene copolymers involve the introduction of the monomer stream into the continuous loop-type reactor along with an appropriate catalyst system to produce the desired olefin homopolymer or copolymer. The resulting polymer is withdrawn from the loop-type reactor in the form of a “fluff” which is then processed to produce the polymer as a raw material in particulate form as pellets or granules. In the case of C3+ alpha olefins, such a propylene or substituted ethylenically unsaturated monomers such as styrene or vinyl chloride, the resulting polymer product may be characterized in terms of stereoregularity, such as in the case of, for example, isotactic polypropylene or syndiotactic polypropylene. Other unsaturated hydrocarbons which can be polymerized or copolymerized with relatively short chain alphaolefins, such as ethylene and propylene include dienes, such as 1,3-butadiene or 1,4-hexadiene or acetylenically unsaturated compounds, such as methylacetylene.